Padgett, who carried his guns in a guitar-case and duffel bag and wore a camouflage helmet, killed himself after shooting one student dead at Reynolds High School in Oregon, they said.
He obtained his weapons -- a military-style AR-15 type rifle, a semi-automatic pistol, a large knife and hundreds of rounds of ammunition -- from a locker at his family home.
"The weapons had been secured, but he defeated the security measures," said Scott Anderson, police chief of Troutdale, outside Portland where yesterday's attack took place.
Despite his injury Rispler made his way to the school office to sound the lockdown alarm, as Padgett -- dressed in jacket designed to carry ammunition and a camouflage sports helmet -- emerged from the locker room.
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"As the shooter was moving through the main hallway he encountered officers who were starting to enter from two separate hallways. At that time he moved into a small restroom," Anderson said.
Anderson hailed the role of Rispler and the first responding officers. "I cannot emphasise enough the role that Mr Rispler and the responding officers in saving many, many lives yesterday," he said.
The Oregon shooting was the fourth in three weeks in the western the United States, following incidents in Santa Barbara, California, Seattle, and Las Vegas last weekend.
Yesterday, President Barack Obama called for national "soul searching," saying mass shootings were "off the charts" in a way no other advanced country would tolerate.